Minimization of parametric diffraction effect in two-beam pumped optical parametric amplification

Parametric diffraction at small intersection angles of pump beams is investigated theoretically as well as experimentally in the case of optical parametric amplification. It is revealed that the parametric diffraction can be avoided at smaller critical intersection angles and proper phase difference of the pump beams. In the case of random phase difference of the pump beams the fluctuations in signal energy can be reduced by increasing the seed energy.